Further extend TypedArray support in d8:

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 68c98aba12ba8d151927cd5c2d7d028d9b3e9d0c..a1ed4225e41a377e176bcf0465f68a404551f4ac 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -1435,6 +1435,9 @@ class JSReceiver: public HeapObject {
   // Return the object's prototype (might be Heap::null_value()).
   inline Object* GetPrototype();
 
+  // Return the constructor function (may be Heap::null_value()).
+  inline Object* GetConstructor();
+
   // Set the object's prototype (only JSReceiver and null are allowed).
   MUST_USE_RESULT MaybeObject* SetPrototype(Object* value,
                                             bool skip_hidden_prototypes);